Nature's Advocate: 2 native Lobelias good for moist woodland gardens

As I worked outdoors yesterday, I couldn’t help but think of the classic summertime song sung by Nat King Cole, “Those Lazy-Hazy-Crazy Days of Summer.”

Patrick Greenwald, MU-Extension Horticulture Specialist

As I worked outdoors yesterday, I couldn’t help but think of the classic summertime song sung by Nat King Cole, “Those Lazy-Hazy-Crazy Days of Summer.” This past week was hot. If you happen to have been fortunate enough to escape the summer heat and float one of the spring-fed rivers in the Missouri Ozarks, you may have noticed the brilliant red cardinal flower or striking great blue lobelia blooming on the edge of the rivers.These are two of my favorite late summer wildflowers easily grown in home gardens and commonly found at local greenhouses. They bloom from July to October and can extend the beauty of a woodland garden well into fall.

Cardinal Flower (Lobelia cardinalis):There is no flower native to Missouri that compares to the true red tubular flowers of the cardinal flower. Growing up to 4 feet tall, the stems stick out above the rest of the woodland plants. Upon flowering, they seem to glow in the late evening sun like a beacon. It prefers rich soil conditions with a high percentage of organic matter. From experience, I have grown them in full sun bog garden conditions, but the plants appear to do better in cooler soils along or in a stream in light shade. Cardinal flowers are one of the ruby-throated hummingbirds’ favorite nectar source, seemingly feeding non-stop while these flowers are in bloom.

Great Blue Lobelia (Lobelia siphilitica):One of those rare true blue flowers of nature, great blue lobelia is found in woodland locations throughout the Ozarks. Blue lobelia can be planted in deep shade, but for best results it should get a little indirect sunlight. On my hikes, I have commonly seen this perennial growing along rocky forested streams or upland wet meadows. With so many yellow wildflowers blooming in late summer, blue lobelia stands out from the rest. Because the flowers are formed in the leaf axils of the stems, and due to its larger herbaceous foliage, blue lobelia can appear weedier than its showy cousin the cardinal flower. Where to plant:Both cardinal flower and blue lobelia are naturally found growing in shaded moist soil environments.Although they can be planted in a rain garden or a drainage ditch, because they require constant moisture, I prefer to plant them along a pond’s edge or in a bog garden (a sunken wetland garden created using an impermeable liner such as a PVC vinyl material commonly filled with peat moss or decomposed organic matter). I treat cardinal flowers in particular as annuals, although they are considered a perennial because of their short lived nature. I find it best to give the plants space to self-seed, being careful the following spring not to “weed out” the volunteer plants that come up along the edge of my bog garden.The seedling plants are easy to transplant and can be moved to a more appropriate spot. It is best to add a layer of light mulch to the top of the plants to prepare them for winter and I find that a loose layer of oak leaves works the best for overwintering plants in my garden.Leaf mulch should be removed when temperatures begin to warm in the spring.Because these lobelias tolerate some shade, they are truly a great addition to any woodland garden. Providing them with a site that retains a little moisture through the heat of summer can provide a lasting display of color from late summer to early autumn.

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